This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. DDegenerative disc disease (DDD) is a common and sometimes painful condition affecting millions. The current standard diagnostic method for DDD involves T2-weighted MR images and the Pfirrmann grading system. T2-weighted MR images are good for showing disc morphological change such as disc flattening, herniation, and osteophytes formation. However, morphology changes in the discs typically occur in the later stages of DDD. The initial sign of DDD is molecular in nature, which involves the breakdown of proteoglycans (PG) in the nucleus pulposus of the disc. In order to detect DDD in its infancy, and to open up the possibility for the development of preventive care strategies, we propose to use sodium MRI to measure changes in PG content, and thus achieve early detection of DDD. In previous studies, sodium MRI has been shown to be able to accurately measure PG content in articular cartilage. In the ex vivo part of this study, we intend to use bovine intervertebral disc as a model to investigate the relationship between sodium MRI and PG concentration. The bovine discs will be imaged using custom-made sodium RF coils. Afterward, PG assay will be performed on the same discs to determine the relationship between sodium MRI and PG concentration. Meanwhile, sodium imaging will be performed in vivo on both healthy and DDD human subjects. ANOVA will be applied to the data in order to determine if a significant difference exist between the sodium MRI of healthy and DDD subjects.